1. Background of the Invention
This invention relates to controllable mobile apparatus such as controllable mobile robots and in particular to controllable mobile apparatuses that permit free roaming operation and still in particular to free roaming mobile apparatus having a dead reckoning guidance system.
In a manufacturing involvement, the use of automated equipment is time and cost effective being the monies spent on labor is substantially reduced. Additionally, in the manufacturing precision circuits and equipments such as semiconductor circuits, it is necessary to manufacture the circuits or devices in a clean environment. Obviously, it is easier to avoid contamination with automation than it is with human participation in the manufacturing process. Consequently, it has been found that having a mobile transportable system for transporting materials cross a factory floor is prferable to the use of conveyor belts or guided material handlers such as those that follow painted stripes, rails, guide wires, etc.
It is desirable to have a free roaming material handler that can be commanded to go to a destination and the material handler is able to guide itself to that destination without operator intervention. In the free roaming system, the mobile apparatus should also have a free roaming operation. therefore, it is necessary to have a dead reckoning guidance system that extrapolates the vehicle position based upon actual wheel behavior and its previous position.
2. Summary of the Invention
A mobile vehicle controller for controlling a mobile apparatus that travels along a commanded path. The mobile vehicle controller has a dead reckoning navigation procedure for navigating the controllable mobile apparatus along the commanded path in response to positions data. The mobile apparatus determines its position and provides the position data. A vision system provides the absolute position to the mobile apparatus. The dead reckoning position data is periodically modifying with the absolute position. The dead reckoning procedure is synchronized with the vision system.
The mobility is provided to the mobile apparatus by a plurality of wheels for providing mobility. A servo motor system provides a means for rotating the plurality of wheels at a controllable speed of rotation, a means for controlling the trajectory of the mobile apparatus by varying the angle of the direction of rotation that predetermined members of the plurality of wheels make with the mobile apparatus means for controlling the speed of rotation of the plurality of wheels.
The dead reckoning procedure determines means distance traversed from the number of rotations of the plurality of wheels and the direction traveled from the angle of the direction of rotation of the plurality of wheels.
A comparison is made of the position data and the absolute position data and the position data is modified by the results of the comparison.
A visual navigation system provides the absolute position of the controllable mobile apparatus in definable coordinate and communicates the definable coordinates to the mobile apparatus.
Synchronization is provided by time stamping the definable coordinates and time offset means for determining the time offset between the time stamp and the time correction means modifies the position data and to additionally modify the position data according to the position difference that results from the time offset.
The visual navigation system obtains an image of the mobile apparatus; converts the image to spatial position and generates absolute position data from the spatial position.
An image of the mobile apparatus is obtained by for providing a defined pattern of lighted points associated with the mobile apparatus, the lighted points being separated from one another by predefined distances and a TV camera obtains an image of the lighted points.
These advantages and objectives of the invention will be apparent from a reading of the specification in conjunction with the figures in which: